Invasive Species Council of British Columbia
Invasive Plant

Scotch thistle

Onopordum acanthium

About This Species

Scotch thistle (Cotton thistle) is a biennial or perennial native to Europe and Asia that reproduces through thousands of seeds that can survive in the soil for over 30 years. The seeds need moisture to germinate. Seeds can spread with the wind, but also in hay and water, and by attaching to clothing or animal fur. It creates dense stands that are extremely difficult for humans and animals to walk through. Scotch thistle is designated as a Regional Noxious Weed by the BC Weed Control Act, as well as a Management species by the BC Provincial Priority Invasive Species List. 

How to Identify

Scotch thistle can grow up to 3 m tall and has stems with spine-edged wings that run up the sides.

Flowers are large pink, purple or sometimes reddish.  

Leaves are irregularly lobed, have sharp yellow spikes, and are covered in woolly hairs that give the foliage a grey-green appearance. 


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